logical operators in lambda

Conoscenza Silente

7 Apr 2010 7 Apr '10

3:17 p.m.

Hi All I am trying to use boost::lambda using logicat operator. I would like to use it in a STL std::find_if call. What I receive is always the same error error: no match for ‘operator==’ in ‘boost::lambda::<unnamed>::_1 == 13’ Do you know what I am doing wrong? Thanks AFG using namespace boost::assign; int main( int argc, char** argv ){ std::vector< int > v; v += 12,13,14,15; bool found_tmp = false; boost::lambda::var_type< bool >::type found( boost::lambda::var(found_tmp) ); std::find_if( v.begin(), v.end(), ( found = ( boost::lambda::_1 == 13 ), return found ) ); }

Attachments:

attachment.html (text/html — 786 bytes)

Show replies by date

Steven Watanabe

7 Apr 7 Apr

3:22 p.m.

AMDG Conoscenza Silente wrote:

...

I am trying to use boost::lambda using logicat operator. I would like to use it in a STL std::find_if call.

What I receive is always the same error error: no match for ‘operator==’ in ‘boost::lambda::<unnamed>::_1 == 13’

Do you know what I am doing wrong? Thanks AFG

using namespace boost::assign;

int main( int argc, char** argv ){

std::vector< int > v; v += 12,13,14,15;

bool found_tmp = false; boost::lambda::var_type< bool >::type found( boost::lambda::var(found_tmp) );

std::find_if( v.begin(), v.end(), ( found = ( boost::lambda::_1 == 13 ), return found ) ); }

Don't try to return found inside the lambda expression. Try bool found = std::find_if(v.begin(), v.end(), boost::lambda::_1 == 13) != v.end(); In Christ, Steven Watanabe

Conoscenza Silente

7:09 p.m.

Thanks a lot! Afg On Wed, Apr 7, 2010 at 5:22 PM, Steven Watanabe wrote:

...

AMDG

Conoscenza Silente wrote:

...
I am trying to use boost::lambda using logicat operator. I would like to use it in a STL std::find_if call.

What I receive is always the same error error: no match for ‘operator==’ in ‘boost::lambda::<unnamed>::_1 == 13’

Do you know what I am doing wrong? Thanks AFG

using namespace boost::assign;

int main( int argc, char** argv ){

std::vector< int > v; v += 12,13,14,15;

bool found_tmp = false; boost::lambda::var_type< bool >::type found( boost::lambda::var(found_tmp) );

std::find_if( v.begin(), v.end(), ( found = ( boost::lambda::_1 == 13 ), return found ) ); }

Don't try to return found inside the lambda expression.

Try

bool found = std::find_if(v.begin(), v.end(), boost::lambda::_1 == 13) != v.end();

In Christ, Steven Watanabe

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

Conoscenza Silente

8 Apr 8 Apr

12:47 p.m.

Hi Steven sorry to bother you again..but the code doesn't work...I didn't try it yesterday when you replied..sorrry for this! I read in the documentation that we need some short-circuiting for logical operators.. On Wed, Apr 7, 2010 at 5:22 PM, Steven Watanabe wrote:

...

AMDG

Conoscenza Silente wrote:

...
I am trying to use boost::lambda using logicat operator. I would like to use it in a STL std::find_if call.

What I receive is always the same error error: no match for ‘operator==’ in ‘boost::lambda::<unnamed>::_1 == 13’

Do you know what I am doing wrong? Thanks AFG

using namespace boost::assign;

int main( int argc, char** argv ){

std::vector< int > v; v += 12,13,14,15;

bool found_tmp = false; boost::lambda::var_type< bool >::type found( boost::lambda::var(found_tmp) );

std::find_if( v.begin(), v.end(), ( found = ( boost::lambda::_1 == 13 ), return found ) ); }

Don't try to return found inside the lambda expression.

Try

bool found = std::find_if(v.begin(), v.end(), boost::lambda::_1 == 13) != v.end();

In Christ, Steven Watanabe

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

Conoscenza Silente

1:17 p.m.

...auch..I figure it out ..I was missing the top header #include "boost/lambda/lambda.hpp"... Thanks again Mn On Thu, Apr 8, 2010 at 2:47 PM, Conoscenza Silente < abruzzoforteegentile@gmail.com> wrote:

...

Hi Steven sorry to bother you again..but the code doesn't work...I didn't try it yesterday when you replied..sorrry for this! I read in the documentation that we need some short-circuiting for logical operators..

On Wed, Apr 7, 2010 at 5:22 PM, Steven Watanabe wrote:

...
AMDG

Conoscenza Silente wrote:

...
I am trying to use boost::lambda using logicat operator. I would like to use it in a STL std::find_if call.

What I receive is always the same error error: no match for ‘operator==’ in ‘boost::lambda::<unnamed>::_1 == 13’

Do you know what I am doing wrong? Thanks AFG

using namespace boost::assign;

int main( int argc, char** argv ){

std::vector< int > v; v += 12,13,14,15;

bool found_tmp = false; boost::lambda::var_type< bool >::type found( boost::lambda::var(found_tmp) );

std::find_if( v.begin(), v.end(), ( found = ( boost::lambda::_1 == 13 ), return found ) ); }

Don't try to return found inside the lambda expression.

Try

bool found = std::find_if(v.begin(), v.end(), boost::lambda::_1 == 13) != v.end();

In Christ, Steven Watanabe

_______________________________________________ Boost-users mailing list Boost-users@lists.boost.org http://lists.boost.org/mailman/listinfo.cgi/boost-users

5435

Age (days ago)

5436

Last active (days ago)

List overview

Download

4 comments

2 participants

participants (2)

Conoscenza Silente
Steven Watanabe